An extendable linkage, such as a telescoping linkage, may be used on a work machine to extend the reach of the work machine, thereby making the work machine usable in a variety of applications. One example of an extendable linkage is an extendable stick (E-stick) on a backhoe loader. An E-stick typically has an outer member and an inner member, which are allowed to slide relative to each other to provide additional reach and digging depth. The amount of extension or slide is typically controlled by a hydraulic cylinder within the E-stick.
Extendable linkages, such as the E-stick, include wear pads disposed between the inner and outer sliding members. The wear pads reduce gaps and play between the members and form low-friction contact points between the members. Over time and use, the thickness of the wear pads decreases because of wear, introducing an increasing amount of play and allowing an increasing amount of movement between the inner and outer members in directions other than a sliding direction. This loose play can reduce an operator's ability to precisely control the location of the work implement.
To reduce the play, wear pads are typically replaced or adjusted when they become worn. Accessing the wear pads on a typical E-stick in order to replace or adjust them typically requires that the inner and outer members be disengaged from each other. Accordingly, disassembly of the entire E-stick is typically necessary to replace or adjust worn wear pads.
Once disassembled, adjustment of the wear pads is often accomplished by placement of shims between the wear pads and the first and second members, compensating for the decreased thickness of the wear pad that occurred by wear. To do this, shims are typically placed on a back surface of the wear pad, moving the front surface of the wear pad in a direction perpendicular to its surface, and closer to the opposing member. Therefore, the front surface of the worn pad is in substantially the same position as the original surface of the pad, reducing the play between the outer and inner members.
U.S. Pat. No. 3,748,807 to Sterner discloses one known wear pad system for an extendable linkage. The '807 patent discloses a telescopic crane boom with trapezoidal-shaped inner and outer boom sections extendable relative to one another. Typical wear pads are disposed below the inner boom section and appear to support the weight of any load. A wedge-shaped lateral guide is connected to a side of the outer boom section, contacts a side of the inner boom section with a sliding face, and separates the sides of the inner and outer boom sections. The guide may be adjusted in a direction perpendicular to the sliding face to guide the inner boom section as it moves relative to the outer boom section.
However, the guide of the '807 patent is not configured to bear loads of the crane. In addition, the guide disclosed in the '807 patent is adjusted perpendicular to its sliding face. This perpendicular adjustment may be difficult when counteracting loads are applied against the pad.
The wear pads disclosed herein are intended to overcome one or more of the disadvantages in the prior art.